The present invention relates to a magnetic recording medium winding apparatus for winding a magnetic recording medium, etc.
In steps of manufacturing the magnetic recording medium such as the magnetic tape, etc., the magnetic recording medium is wound by the magnetic recording medium winding apparatus like a roll to feed the magnetic recording medium to next steps when processes in respective steps are completed. In this case, the thinner thickness and the higher density of the recent magnetic recording medium are advanced, such medium is formed as a very thin layer such that a total thickness is about 5 xcexcm, and the surface property of the medium is also improved. Therefore, the failure during the winding of the magnetic recording medium becomes the big problem.
First, if the exclusion of the air between the magnetic recording mediums is not sufficient when the magnetic recording medium is wound like a roll, the so-called xe2x80x9cloose windingxe2x80x9d of the original roll of magnetic recording medium is caused. Thus, the winding mode is not stable, and the magnetic recording medium cannot be supplied stably to the next step. Since the magnetic recording mediums slides easily if the surface property of the magnetic recording mediums is better, this problem becomes prominent. Also, if a large amount of the air still remains in the original roll of magnetic recording medium, the air is released with the lapse of time. Thus, there is caused the problem such than the magnetic recording medium is folded in the space, from which the air is released, to generate the wrinkle.
Therefore, in order to prevent the xe2x80x9cloose windingxe2x80x9d, it may be considered that, when the magnetic recording medium is wound while pushing the magnetic recording medium against the original roll of magnetic recording medium by the pushing roller, or the like, the pushing pressure is increased. However, if the exclusion of the air in the inside of the original roll of magnetic recording medium is executed excessively, the large stress is loaded onto the magnetic recording medium. Therefore, the magnetic recording medium made of elastic material such as PET, or the like, for example, is deformed during the winding, and thus sometimes the wrinkle is generated during the winding. In this manner, there is the problem how to adjust the setting of the air since the adjustment of the exclusion of the air is delicate.
Also, the magnetic recording medium is subjected to various tensions in the winding and in respective steps up to now and is distorted. Thus, if the magnetic recording medium is employed as it is, the residual strain brings about the defective quality such as the skew, etc. and the defective process in which the wrinkle is generated in the inside of the original roll of magnetic recording medium in the peripheral direction and the width direction after the winding has been completed. For this reason, sometimes there is applied the strain removing step in which the strain is removed by applying the annealing process for several hours or several days after the winding. In this case, if the strain is removed, the magnetic recording medium is shrunk and is deformed to reduce a diameter of the original roll of magnetic recording medium. In this case, if the air exists by a predetermined amount in the original roll of magnetic recording medium, the magnetic recording medium can be shrunk because the air is excluded. Unless the air does not exist by the predetermined amount, the magnetic recording medium cannot be shrunk, so that the strain cannot be removed.
In addition, if the pushing force of the pushing roller is increased, the residual air amount in the original roll of magnetic recording medium can be reduced, so that the magnetic recording medium can be wound tightly. However, if the magnetic recording medium is a thin layer, the tension must be lowered in view of the thickness and the strength of the magnetic recording medium. If the winding is executed while lowering the tension, the exclusion of the air in the original roll of magnetic recording medium is not carried out successively. Thus, the above defective process appears frequently, and the failures such as the so-called rough winding, in which the unevenness is generated on the side surfaces, the loose winding, etc. are generated.
In this manner, if the residual air amount contained in the original roll of magnetic recording medium is set too large or too small, the failure is caused. Therefore, the air amount that enters into the inside of the original roll of magnetic recording medium during the winding of the magnetic recording medium is adjusted by adjusting the pushing force of the pushing roller against the original roll of magnetic recording medium.
As one adjusting approach, as shown in FIG. 6, there is the method of pushing the pushing roller 25 against the original roll of magnetic recording medium 23 during the winding and then adjusting the air amount that is sandwiched between respective layers of the original roll of magnetic recording medium 23 by the pushing roller 25. This pushing roller 25 is fitted rotatably to the top end of the arm member 55 that is turned around the rotation shaft 53. Then, the gear portion 63 of the arm member 55 is driven by moving upward and downward the rack 61, which is provided to the side surface of the piston rod 59, by virtue of the air cylinder 57. Therefore, the arm member 55 is turned around the rotation shaft 53 to push the pushing roller 25 against the original roll of magnetic recording medium 23.
However, in the above magnetic recording medium winding apparatus 51, as shown in FIG. 7, because of the influences of the sliding resistance of the sliding surface 65 between the piston rod 59 and the air cylinder 57, the resistance between the piston rod 59 and the gear portions 61, 63, the variation in the fitting precision of respective portions, etc., the pushing pressure of the pushing roller 25 against the original roll of magnetic recording medium 23 does not coincide with the set pressure. Thus, it is difficult to set precisely the actual pushing pressure.
Also, the conditions such as the pressure that causes the wrinkle in the magnetic recording medium, etc. are not fixed constant because of the above influences, and the individual difference appears in the employed magnetic recording medium winding apparatuses 51. Therefore, the winding conditions must be set individually in each magnetic recording medium winding apparatus 51, which makes the manufacturing steps complicated and causes the increase in cost.
The present invention has been made in view of such problems in the prior art, and it is an object of the present invention to provide a magnetic recording medium winding apparatus capable of setting precisely a pushing force of a pushing roller against an original roll of magnetic recording medium and particularly capable of winding stably a thin magnetic recording medium, to which a pressure must be applied delicately, in high quality.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a magnetic recording medium winding apparatus for rolling up an original roll of the magnetic recording medium, comprising: an arm member rotatably supporting a pushing roller at one end side thereof and supported turnably around the other end side thereof; a driving unit turning the arm member to push the pushing roller against the original roll of magnetic recording medium at a predetermined set pressure while rolling up the original roll; a strain sensing unit sensing a strain generated in the arm member during a pushing by the driving unit; and a control unit calculating a pressure of the pushing roller against the original roll of magnetic recording medium based on a sensed signal of the strain sensing unit and also feedback-controlling the driving unit such that the calculated pressure coincides with the set pressure at the driving unit.
According to a second aspect of the present invention, there is provided a magnetic recording medium winding apparatus as set forth in the first aspect, wherein the magnetic recording medium is magnetic tape.
According to a third aspect of the present invention, there is provided a magnetic recording medium winding apparatus as set forth in the first aspect, wherein the arm member comprises a sectorial gear portion provided to a top end portion of the other end portion thereof, the driving unit comprises an air cylinder, and the gear portion engages with a rack fitted to a piston rod of the air cylinder.
According to a fourth aspect of the present invention, there is provided a magnetic recording medium winding apparatus as set forth in first aspect, further comprising a strain gauge as the strain sensing unit fitted to a substantially center portion of the arm member, wherein a strain signal of the arm member, which is sensed by the strain gauge, is amplified by an amplifier and then input into the control unit.
According to a fifth aspect of the present invention, there is provided a magnetic recording medium winding method, comprising steps of: preparing an arm member rotatably supporting a pushing roller at one end side thereof and supported turnably around the other end side thereof; rolling up an original roll of the magnetic recording medium; turning the arm member to push the pushing roller against the original roll of magnetic recording medium at a predetermined set pressure while rolling up the original roll; sensing a strain generated in the arm member during a pushing of the pushing roller; calculating a pressure of the pushing roller against the original roll of magnetic recording medium based on the strain of the arm member; and feedback-controlling the turning of the arm member such that the calculated pressure coincides with the set pressure.
According to this magnetic recording medium winding apparatus, when the magnetic recording medium is wound on the original roll of magnetic recording medium, the pushing roller is pushed against the original roll of magnetic recording medium by the driving unit via the arm member, and then the strain in the arm member caused at this time is sensed by the strain sensing unit and fed back to the control unit. The pressure of the pushing roller is calculated from the sensed strain by virtue of the reduction in the control unit, and then the driving unit is feedback-controlled by comparing this pressure with the set pressure set to the driving unit such that both pressures coincide with each other. Therefore, the pressure control can be carried out with high precision.
Also, if the correlation between the strain and the pressure of the pushing roller is detected previously experimentally, the pressure of the pushing roller is calculated from the strain by virtue of the reduction. Thus, the sensing of the pressure to the original roll of magnetic recording medium during the winding, which was not possible until now, can be achieved. In addition, the pressure calculated based on the strain sensed in this manner contains all error factors such as the fitting methods of the driving unit, the arm member, etc. Thus, if the above correlation is sensed previously every winding apparatus, the original roll of magnetic recording medium can always be wound at the constant pressure by the different winding apparatus.